Monitoring attachment for an extrusion apparatus



Oct. 18, 1966 E- s. HANNIS MDNITORING ATTACHMENT FOR AN EXTRUSION APPARATUS 5 Sheets-Sheet 1 Filed July 8, 1965 INVEN'TUFP L E. 5. HFJNN/E' aw 4 M Oct. 18, 1966 E. s. HANNIS MONITORING ATTACHMENT FOR AN EXTRUSION APPARATUS Filed July 8, 1965 5 Sheets-Sheet 2 Oct. 18, 1966 as. HANNIS 3,278,988

' RANET IONAPP Filed July 1965 5 Sheets-Sheet 5 7lQ-E l H l 67 !Hill I United States Patent This invention relates to a monitoring attachment for an extrusion apparatus, and more particularly, to a monitoring attachment which simultaneously extrudes a reference tape as an insulating jacket is extruded on an elongated article, such as a cable.

In the manufacture of certain types of telephone cables, a core comprising a plurality of individually insulated conductors is covered by a conductive metal sheath. A non-conductive material is extruded onto the sheath to provide a jacket for the protection of the cable.

Occasionally, portions of the jacket stress-crack, that is, minute cracks appear in the jacket which permit moisture to enter the cable, thereby rendering the cable unacceptable for service. If the cracks are detected prior to the installation of the cable in the field, it is relatively easy to repair the jacket; however, this is not the usual case. Sometimes, the cracks are not detected until after the cable has been installed and in these instances the cable must be replaced. Thus, it is desirable to ascertain the reasons for the stress-cracking of cable jackets.

In one method used to ascertain these reasons, the jacket material is molded into strips and chemical tests are performed on the strips. The results of these tests 'are inconclusive because (1) the strips are not produced under equivalent conditions as the cable jacket, (2) there is no correlation between the batch of material used for making the strip and the jacket which has stress-cracked, and (3) the molding of the jacket material is not an equivalent process to the extrusion thereof.

The monitoring attachment of this invention produces a reference tape or strip of substantially the same thickness, and under substantially equivalent manufacturing conditions, as the jacket being extruded onto the sheath of a cable. The tape is numerically or otherwise correlated to the. particular cable being produced. If a particular cable stress-cracks, the appropriate tape is analyzed to ascertain the reasons for such stress-cracking; i.e., whether the stress-cracking was due to the extrusion process, the jacket material, the field environment of the cable, or the like.

Accordingly, an object of this invention is to provide a new and improved monitoring attachment for an extrusion apparatus. Another object is to provide a new and improved monitoring attachment for an extrusion apparatus wherein a reference tape is extruded simultaneously with, and under substantially equivalent manufacturing conditions, as the extrusion of an extrudable material onto an article.

Another object is to provide a new and improved monitoring attachment for an extrusion apparatus which simultaneously extrudes a reference tape as the insulating jacket on a cable is extruded. A corollary object is to provide such a monitoring attachment wherein the reference tape is substantially the same thickness as the jacket.

With these and other objects in view, a monitoring attachment for an extrusion apparatus, illustarting certain features of the invention, includes a device which bypasses a portion of an extrudable material at a predetermined rate from the extrusion apparatus. The bypassed material is fed to a facility which produces a reference tape simultaneously with the extrusion of the material onto an article.

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In a specific embodiment of the monitoring attachment, a valve is connected to the throat of an extrusion apparatus for bypassing therefrom a portion of the extrudable material at a predetermined rate to a series of ducts which terminate in a reservoir. The bypassed mateiral is fed from the reservoir through a guideway which terminates in an outlet to produce a reference tape. One of the dimensions of the outlet is adjustable such that the reference tape has a thickness substantially equal to that of a jacket being extruded onto the sheath of a cable.

In order to prevent the edges of the reference tape from curling due to the tape being air cooled on one side when fed to a takeup conveyor, a new takeup device has been provided. The new takeup device cooperates with the monitoring attachment of this invention, to subject both sides of the tape to substantially identical thermal conditions to prevent curling of its edges.

Other objects and advantages of the invention will become apparent by reference to the following detailed specification and drawings, wherein:

FIG. 1 is a cross-sectional View, incorporating certain features of the invention, of a monitoring attachment for an extrusion apparatus;

FIG. 2 is a partial schematic view of a conventional extrusion apparatus showing the monitoring attachment of the invention connected to the throat of the apparatus;

FIG. 3 is a vertical section view taken along line 3-3 of FIG. 1;

FIG. 4 is a vertical section View taken along line 4-4 of FIG. 1; and

FIG. 5 is a schematic view of an apparatus for maintaining a reference tape, produced by the monitoring attachment, in a flat condition.

Referring to FIG. 2, there is schematically shown the monitoring attachment of the invention, generally indicated by reference numeral 10, connected to the neck 16 of a conventional extrusion apparatus. The extrusion apparatus includes a barrel 17, containing a screw 18 for advancing extrudable material 19 to a throat 21 of the apparatus. Material 19 is then advanced to a crosshead 22, through which a cable 23 passes, and in which material 19 is extruded to provide a protective jacket 24 on a metal sheath 26 of a cable 23. Material 19 may be any of a number of suitable materials, for example, rubber, a plastic such as polyethylene or polyvinylchloride, or the like.

In FIG. 1, neck 16 of the extrusion apparatus includes an opening 25 which receives a throttle valve 27. Throttle valve 27 includes a plug 28 whose end surface is machined to the same arcuate radius as the inner periphery of throat 21. Plug 28 is movable toward or away from the inner periphery of throat 21 by a screw-type plug control 29. Valve 27 also includes a valve face 36 which is movable towards or away from a valve seat 37, formed in opening 25, by a screw-type valve control 38.

Neck 16 of the extrusion apparatus also includes an opening 30 which receives a hollow conduit 39. One end of the conduit communicates with a channel 41 of opening 30 which is adjacent to valve seat 37.

One end of upper hollow duct 42 is connected to conduit 39, and its other end is connected to a lower hollow duct 43. Ducts 42 and 43 are joined together by a coupling 44 which includes a bearing 45, such that lower duct 43 is rotatable about upper duct 42.

A housing 46 is connected to lower duct 43, and contains a cylindrical reservoir 47 having an upper passageway 48 extending from the top thereof which communicates with the opening in lower duct 43.

Thus, when plug 28 is withdrawn such that its end surface is flush with valve face 36, and valve face 36 is withdrawn from its valve seat 37, as shown in FIG. 1,

there is a continuous passageway from throat 21 to reservoir 47.

A die 49 is secured to housing 46 and contains a tapered guideway 56 which communicates with a lateral passageway 57 extending from reservoir 47, the guideway terminating in a flattened outlet 58.

With reference to FIG. 3, upper passageway 48 of reservoir 47 comprises four bores 61-64 which feed reservoir 47. The two outer bores, 61 and 64, are of a greater diameter than the two inner bores, 62 and 63, to provide a proportionally greater flow of material 19 towards the ends of reservoir 47, thus insuring substantially equal pressure throughout the reservoir. A removable plug 66 is mounted in each side of housing .46

to define the edges, and hence the capacity, of reservoir 47. Since plugs 66 are removable, cleaning of reservoir 47 is facilitated.

In FIGS. 1 and 4, a plate 67 is slideably mounted on the face of die 49 and has elongated slots 68 formed therein. Slots 68 are slideable under headed bolts 69 such that plate 67 is slideable up and down to adjust the dimension (2) of outlet 58.

Operation With reference to FIG. 1, dimension (2) of outlet 58 is adjusted by positioning plate 67, such that a reference tape 71 extruded from outlet 58 draws down to a thickness substantially equal to the thickness of jacket 24 which is being extruded onto sheath 26 of cable 23 (FIG. 2). Plug control 29 is rotated to move plug 28 until its end surface is flush with valve face 36. Valve control 38 is then rotated to move valve face 36 until it is at a selected position across the opening of channel 41, thereby permitting a predetermined amount of plastic material 19 to be bypassed from throat 21 at a predetermined rate.

Plastic material 19 flows into channel 41 and through the passageways in conduit 39 and ducts 42 and 43 to fill reservoir 47; whereupon, plastic material 19 flows in guideway 56 and is extruded as a flat tape 71 (FIG. from outlet 58, tape 71 being substantially the same thickness as jacket 24. Since ducts 42 and 43 are connected through bearing 45, lower duct 43, housing 46, and die 49 are rotatable to a desired position to facilitate takeup of tape 71.

In an illustrative use of the monitoring attachment, it is connected to the throat of a conventional extrusion apparatus in which plastic material 19 is under 10,000 p.s.i. .Throttle valve 27 isselectively operated to position valve face 36 and plug 28, such that plasticmaterial 19 flows from throat 21 to outlet 58. Under these conditions, approximately one inch of reference tape 71 (FIG. 5) is extruded from outlet 58 for every 25 feet of cable 23 produced. a

It is to be understood that the pressures, dimensions, and rate of production, set forth above with respect to the operation of the monitoring attachment, are only illustrative, and may be varied depending upon actual manufacturing requirements.

Take-up apparatus for reference tape With reference to FIG. 5, an apparatus for maintaining reference 'tape 71 in a flat condition is only shown schematically, since it does not form a part of the invention. An upper continuous belt 76 is rotated about a plurality of rollers 77, opposite a lower continuous belt 78 which is rotated about a plurality of rollers 79. The belts and rollers are mounted in frames (not shown) connected together by a hinge assembly 81, which permits the adjustment of the space between belts 76 and 78 to accommodate reference tapes 71 of different thicknesses. Belts 76 and 78 may be made of any of a number of temperature stable material, for example Teflon.

A temperature control device 82, comprising a plurality of conventional heating elements and cooling elements (not shown), is mounted on supports 83 opposite one another to impose identical temperature conditions on the portions of belts 76 and 78 between which tape 71.

wide variety of conventional apparatus. for extruding,

material onto articles, and is not to be construed as being limited to use with an apparatus for extruding a plastic jacket on a telephone or other type cable. Further, the monitoring attachment need not necessarily be connected to the throat of an extrusion apparatus, but may be connected to other suitable portions of such apparatus.

It is to be understood that the above-described embodiment is only illustrative of the principles of the invention, and other embodiments may be devised without departing from the scope of the invention.

What is claimed is:

1. In an apparatus for extruding an extrudable material onto a moving elongated article, a monitoring attach ment comprising:

means connectable to an extruding apparatus for bypassing a portion of teh material from the apparatus at a predetermined rate, and

means for receiving the bypassed material and for producing a reference tape therefrom simultaneous- I 1y with the extrusion of the material onto the article. 2. The monitoring attachment according to claim .1, wherein the bypassing means includes means for selectively controlling the predetermined rate of flow of bypassed material.

ing:

a housing having a reservoir contained therein, the

reservoir having an inlet and an outlet, and

means, connectable to an extruding apparatus, for bypassing a portion of the material from the extruding apparatus at a predetermined rate into the reservoir to extrude a reference tape from the outlet.

6. In the extruding of an extrudable material onto an article,

means for extruding an extrudable material,

means connected to the extruding means for bypassing from the extruding means an amount of material which is proportional to the. amount of material being extruded onto the article, and

means for receiving the bypassed material and for producing a reference tape therefrom simultaneously with the extrusion of the material onto an article. i

7. In an extrusion apparatus having facilities for advancing extrudable material to the throat of the apparatus and then to a crosshead, a continuously-running elongated article, such as a cable core, passing through the crosshead whereat the material is extruded onto the cable, the combination with the extrusion apparatus of::

a valve connected to the throat of the apparatus for continuously bypassing a predetermined amountof the material away from the throat, a housing having a reservoir contained therein, the reservoir having an inlet and an outlet through which the bypassed material is extruded to produce a reference tape, and

means connecting the valve with the inlet of the reservoir.

8. In the extrusion apparatus according to claim 7, wherein the valve includes means for selectively adjusting the amount of material which is continuously bypassed from the throat to the reservoir, thereby controlling the rate at which the reference tape is extruded from the outlet.

9. In the extrusion apparatus according to claim 7, further in combination, means for selectively adjusting the perimeter dimensions of the outlet, thereby controlling the thickness of the reference tape being extruded from the outlet.

10. In the extrusion apparatus according to claim 7, further in combination:

means for controlling the valve to selectively adjust the amount of material which is continuously bypassed from the throat to the reservoir, thereby controlling the rate at which the reference tape is extruded from the outlet, and

means for selectively adjusting the perimeter dimensions of the outlet, thereby controlling the thickness of the reference tape being extruded from the outlet.

11. In an extrusion apparatus having facilities for advancing extrudable material to the throat of the apparatus and then to a crosshead, a continuously-running cable passing through the crosshead whereat the material is extruded onto the cable, the combination with the extrusion apparatus of:

a housing having a reservoir contained therein, the

reservoir having an inlet passage and outlet passage,

a valve connected to the throat of the extrusion apparatus for continuously bypassing a portion of the material from the throat to the reservoir at a predetermined rate,

control means for the valve for selectively varying the rate of bypassing the material from the throat,

ducts for interconnecting the valve and the inlet of the reservoir,

a die, connected to the housing, having a guideway contained therein which communicates with the outlet passage of the reservoir, the guideway terminating in a die opening, the bypassed material being extruded from the die opening to produce a reference tape, and

a plate movably mounted on the die for selectively adjusting at least one dimension of the die opening, thereby selectively controlling the thickness of the reference tape, the rate of extruding the reference tape being selectively controlled by the valve control means.

12. In the extrusion apparatus according to claim 11, wherein the valve has a plug whose end surface has the same contour as the inner periphery of the throat.

13. In the extrusion apparatus according to claim 1'1, wherein the ducts are movable relative to each other to permit a selective orientation of the die opening.

14. In the extrusion apparatus according to claim 11, wherein the die opening has a rectangular configuration.

References Cited by the Examiner UNITED STATES PATENTS 2,105,812 1/1938 Gordon 1813 XR 2,742,669 4/1956 Rhodes 18-42 XR 3,114,170 12/1963 Blakey et al. 18-12 WILLIAM J. STEPHENSON, Primary Examiner. 

1. IN AN APPARATUS FOR EXTRUDING AN EXTRUDABLE MATERIAL ONTO A MOVING ELONGATED ARTICLE, A MONITORING ATTACHMENT COMPRISING: MEANS CONNECTABLE TO AN EXTRUDING APPARATUS FOR BYPASSING A PORTION OF TEH MATERIAL FROM THE APPARATUS AT A PREDETERMINED RATE, AND MEANS FOR RECEIVING THE BYPASSED MATERIAL AND FOR PRODUCING A REFERENCE TAPE THEREFROM SIMULTANEOUS LY WITH THE EXTRUSION OF THE MATERIAL ONTO THE ARTICLE. 